Air embolism: possible role of surfactant on recompression

1982 ◽  
Vol 52 (1) ◽  
pp. 119-123 ◽  
Author(s):  
B. A. Hills ◽  
R. E. Barrow
Keyword(s):  
Surface Tension ◽  
Decompression Sickness ◽  
Air Embolism ◽  
Pulmonary Vasculature ◽  
Physiological Conditions ◽  
Arterial Blood ◽  
Dipalmitoyl Lecithin ◽  
Reduce Surface Tension ◽  
The Relationship

The relationship between surface tension and surface area has been measured on each of three common pulmonary surfactants - dipalmitoyl lecithin (DPL), dipalmitoyl phosphatidylethanolamine, and sphyngomyelin-under simultaneously simulated physiological conditions. These are selected to simulate the state of any surfactant that has migrated onto the surface of venous bubbles filtered by the pulmonary vasculature. It is concluded that, in the absence of shunt vessels, only DPL could reduce surface tension enough to allow pulmonary gas emboli to escape into arterial blood and then only after compression. This finding is discussed in relation to the delay in any appearance of bubbles in arterial blood and the possible facilitation of the release of asymptomatic lung bubbles by recompression therapy. The suggestion is made to reconsider stopping recompression of a subject with peripheral decompression sickness (the bends) at the depth of relief rather than risk releasing pulmonary gas emboli by further recompression. It is also demonstrated how the introduction of 1-min stops into compression can avoid surface tension falling to the low values at which it is theoretically possible for venous bubbles to escape into arterial blood during pulmonary hypertension.

scholarly journals Influence of moisture content on the contact angle and surface tension measured on birch wood surfaces

2021 ◽  
Author(s):  
Rami Benkreif ◽  
Fatima Zohra Brahmia ◽  
Csilla Csiha
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Moisture Content ◽  
Solid Wood ◽  
Contact Angles ◽  
Surface Moisture ◽  
Wood Coatings ◽  
The Relationship ◽  
Wood Surfaces

AbstractSurface tension of solid wood surfaces affects the wettability and thus the adhesion of various adhesives and wood coatings. By measuring the contact angle of the wood, the surface tension can be calculated based on the Young-Dupré equation. Several publications have reported on contact angle measured with different test liquids, under different conditions. Results can only be compared if the test conditions are similar. While the roles of the drop volume, image shooting time etc., are widely recognized, the role of the wood surface moisture content (MC) is not evaluated in detail. In this study, the effect of wood moisture content on contact angle values, measured with distilled water and diiodomethane, on sanded birch (Betula pendula) surfaces was investigated, in order to find the relationship between them. With increasing MC from approximately 6% to 30%, increasing contact angle (decreasing surface tension) values were measured according to a logarithmic function. The function makes possible the calculation of contact angles that correspond to different MCs.

Ventilatory response to moderate and severe hypoxia in adult dogs: role of endorphins

1988 ◽  
Vol 65 (3) ◽  
pp. 1383-1388 ◽  
Author(s):  
J. I. Schaeffer ◽  
G. G. Haddad
Keyword(s):  
Ventilatory Response ◽  
Minute Ventilation ◽  
Severe Hypoxia ◽  
Moderate Hypoxia ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
Before And After ◽  
The Relationship ◽  
Arterial Po2

To determine the role of opioids in modulating the ventilatory response to moderate or severe hypoxia, we studied ventilation in six chronically instrumented awake adult dogs during hypoxia before and after naloxone administration. Parenteral naloxone (200 micrograms/kg) significantly increased instantaneous minute ventilation (VT/TT) during severe hypoxia, (inspired O2 fraction = 0.07, arterial PO2 = 28-35 Torr); however, consistent effects during moderate hypoxia (inspired O2 fraction = 0.12, arterial PO2 = 40-47 Torr) could not be demonstrated. Parenteral naloxone increased O2 consumption (VO2) in severe hypoxia as well. Despite significant increases in ventilation post-naloxone during severe hypoxia, arterial blood gas tensions remained the same. Control studies revealed that neither saline nor naloxone produced a respiratory effect during normoxia; also the preservative vehicle of naloxone induced no change in ventilation during severe hypoxia. These data suggest that, in adult dogs, endorphins are released and act to restrain ventilation during severe hypoxia; the relationship between endorphin release and moderate hypoxia is less consistent. The observed increase in ventilation post-naloxone during severe hypoxia is accompanied by an increase in metabolic rate, explaining the isocapnic response.

scholarly journals Obesity in the Pathogenesis of type 2 Diabetes

KYAMC Journal ◽  
2017 ◽  
Vol 4 (1) ◽  
pp. 357-361 ◽  
Author(s):  
Farzana Mahmuda ◽  
Marufa Akhter ◽  
Ronjon Kumer Nath
Keyword(s):  
Type 2 Diabetes ◽  
Body Weight Regulation ◽  
Physiological Conditions ◽  
Quantitative Genetic ◽  
Sedentary Life ◽  
Sedentary Life Style ◽  
The Relationship ◽  
Diabetes And Obesity

The article reviews the relationship between type 2 diabetes and obesity. This also includes types of obesity and it's genetic predisposition. The modern generalization of sedentary life style and caloric abundance has created new physiological conditions capable of changing the level of expression of a number of genes involved in fuel metabolism and body weight regulation. In this article, we underscore the importance of obesity in relation to disorders of diverse etiologies characterized by disturbances of free fatty acids, visceral adiposity and insulin resistance. Further, we have investigated the role of selecting the traits to be subjected to quantitative genetic analysis in the occurrence of obesity.KYAMC Journal Vol. 4, No.-1, July 2013, Page 357-361

A method of producing calibrated microtubules for air embolism studies

1981 ◽  
Vol 51 (2) ◽  
pp. 524-528 ◽  
Author(s):  
B. A. Hills ◽  
B. D. Butler
Keyword(s):  
Surface Tension ◽  
Gas Injection ◽  
Air Embolism ◽  
Breathing Frequency ◽  
Differential Absorption ◽  
Plasma Surface ◽  
Arterial Blood ◽  
Anesthetized Dogs ◽  
Injection Methods ◽  
Physiological Values

Utilizing the differential absorption techniques in conjunction with gas injection methods has enabled the production of calibrated microtubules with diameters ranging from 14 to 300 micron. Nitrogen was blended with CO2, the "diluent" gas, to produce the initial bubbles, while tris(hydroxymethyl)-aminomethane hydrochloride (THAM) was used as an absorbent to remove the diluent gas from the bubbles. Hence, the diameters of the initial bubbles were significantly reduced with only the inert gas remaining. The Coulter counter was used for immediate size monitoring of the microtubules. To verify the inertness of the absorbent medium, nine anesthetized dogs were infused with increasing amounts of the solution. In five of the animals plasma surface tension and pH (arterial) were measured, while in the remaining four arterial blood pressure, heart rate, breathing frequency, and pulmonary artery pressure was measured before, during, and after the injections. Changes in plasma surface tension and pH were minimal while acceptable physiological values were recorded, all of which were in agreement with previous investigations. Differential absorption techniques provided a reliable means for producing calibrated micro-bubbles for air embolism studies.

Diaphragmatic pressure-flow relationship during hemorrhagic shock: role of nitric oxide

1994 ◽  
Vol 77 (5) ◽  
pp. 2244-2249 ◽  
Author(s):  
M. E. Ward ◽  
S. N. Hussain
Keyword(s):  
Nitric Oxide ◽  
Inflection Point ◽  
Treated Group ◽  
Least Squares Regression ◽  
Arterial Perfusion ◽  
Arterial Blood ◽  
Left Femoral Artery ◽  
Phrenic Artery ◽  
The Relationship

In the vascularly isolated resting and contracting (3 Hz) canine hemidiaphragm, we studied the effect of intra-arterial infusion of the nitric oxide (NO) inhibitor NG-nitro-L-arginine (LNA) on the relationship between phrenic arterial perfusion pressure (Pphr) and blood flow (Qphr). In separate groups of animals, either saline or LNA (final concn 6 x 10(-4) M) was infused into the phrenic artery over 20 min. The diaphragm was then autoperfused by diverting flow from the left femoral artery. Arterial blood pressure was reduced in stages by controlled hemorrhage. The Pphr-to-Qphr relationship was plotted for each animal, and the third-order polynomial of best fit was determined by least squares regression. The inflection point of this relationship was determined for each animal. In the contracting and resting diaphragms, the inflection point corresponded to Pphr values of 83.6 +/- 4.7 and 72.5 +/- 6.8 mmHg, respectively, in the saline-treated group compared with 86.2 +/- 2.7 and 76.8 +/- 5.1 mmHg, respectively, in the LNA-treated group. In the contracting diaphragm, LNA reduced Qphr uniformly across the entire range of perfusion pressures. In the resting diaphragm, the effect of LNA was not uniform. At perfusion pressures below the inflection point, the flow was reduced in proportion to the reduction in inflection point flow. At higher perfusion pressures, Qphr was decreased to a greater extent than could be accounted for by the change in inflection point flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Na+ transport properties of isolated rat parotid acini

1990 ◽  
Vol 259 (6) ◽  
pp. G1044-G1055 ◽  
Author(s):  
S. Dissing ◽  
B. Nauntofte
Keyword(s):  
Transport Properties ◽  
Na Transport ◽  
Cell Water ◽  
Exchange System ◽  
Physiological Conditions ◽  
Cotransport System ◽  
Rat Parotid ◽  
The Relationship ◽  
Na Uptake

The effect of carbachol stimulation on the Na+ transport properties of rat parotid acini was characterized. Upon stimulation, the acinar Na+ concentration increased from 20 to 70 mM within 25 s, whereafter a backregulation toward the prestimulatory level was observed, mediated by the Na(+)-K+ pump. The transport mechanisms responsible for the net Na+ uptake observed between 10 and 20 s after carbachol stimulation in a Krebs-Ringer-bicarbonate medium (KRB) consisted of a dimethylamiloride-sensitive Na(+)-H+ exchange system (3.5 mmol.liter cell water-1.s-1 or approximately 75% of the total Na+ influx) and a bumetanide-sensitive cotransport system (of approximately 15%). The data are consistent with the residual influx being mediated by amiloride-sensitive Na+ channels. In unstimulated acini acidified by a NH4+ prepulse technique, the relationship between intracellular pH (pHi) and the rate of acinar Na(+)-H+ exchange was determined. At pHi 6.5 the rate of Na(+)-H+ exchange in a KRB medium amounted to 1.2 mmol.liter cell water-1.s-1 and ceased when pHi had recovered to 7.2. It was concluded that under physiological conditions carbachol stimulation activates Na(+)-H+ exchange, an effect that is responsible for the major part of the Na+ gain after stimulation. The role of cotransport in mediating net Cl- uptake against an electrochemical gradient was investigated. It was found that when the Na+ gradient is strongly reduced (in a 20 mM Na+ medium) a Cl(-)-HCO3- exchange system can mediate a net Cl- uptake at a rate similar to the rate observed in a medium containing high Na+. The results are compatible with both Cl(-)-HCO3- exchange and cotransport keeping an intracellular Cl- concentration above the electrochemical equilibrium under physiological conditions.

HIGH TORSIONAL ENERGY DISULFIDES: RELATIONSHIP BETWEEN CROSS-STRAND DISULFIDES AND RIGHT-HANDED STAPLES

2006 ◽  
Vol 04 (01) ◽  
pp. 155-168 ◽  
Author(s):  
NAOMI L. HAWORTH ◽  
LINA L. FENG ◽  
MERRIDEE A. WOUTERS
Keyword(s):  
Protein Function ◽  
Protein Structures ◽  
Redox Activity ◽  
Physiological Conditions ◽  
Protein Secondary Structures ◽  
Torsional Energy ◽  
Redox Active ◽  
The Relationship ◽  
Β Sheet

Redox-active disulfides are capable of being oxidized and reduced under physiological conditions. The enzymatic role of redox-active disulfides in thiol-disulfide reductases is well-known, but redox-active disulfides are also present in non-enzymatic protein structures where they may act as switches of protein function. Here, we examine disulfides linking adjacent β-strands (cross-strand disulfides), which have been reported to be redox-active. Our previous work has established that these cross-strand disulfides have high torsional energies, a quantity likely to be related to the ease with which the disulfide is reduced. We examine the relationship between conformations of disulfides and their location in protein secondary structures. By identifying the overlap between cross-strand disulfides and various conformations, we wish to address whether the high torsional energy of a cross-strand disulfide is sufficient to confer redox activity or whether other factors, such as the presence of the cross-strand disulfide in a strained β-sheet, are required.

Choosing a Markov blanket

2020 ◽  
Vol 43 ◽  
Author(s):  
Thomas Parr
Keyword(s):  
Markov Blanket ◽  
Target Article ◽  
The Relationship

Abstract This commentary focuses upon the relationship between two themes in the target article: the ways in which a Markov blanket may be defined and the role of precision and salience in mediating the interactions between what is internal and external to a system. These each rest upon the different perspectives we might take while “choosing” a Markov blanket.

Staring Down Death

Crisis ◽  
2016 ◽  
Vol 37 (3) ◽  
pp. 212-217 ◽  
Author(s):  
Thomas E. Joiner ◽  
Melanie A. Hom ◽  
Megan L. Rogers ◽  
Carol Chu ◽  
Ian H. Stanley ◽  
...  
Keyword(s):  
Suicide Risk ◽  
Clinical Utility ◽  
Blink Rate ◽  
Specific Task ◽  
Careful Planning ◽  
Eye Blink ◽  
Eye Blinks ◽  
Potential Clinical Utility ◽  
The Relationship

Abstract. Background: Lowered eye blink rate may be a clinically useful indicator of acute, imminent, and severe suicide risk. Diminished eye blink rates are often seen among individuals engaged in heightened concentration on a specific task that requires careful planning and attention. Indeed, overcoming one’s biological instinct for survival through suicide necessitates premeditation and concentration; thus, a diminished eye blink rate may signal imminent suicidality. Aims: This article aims to spur research and clinical inquiry into the role of eye blinks as an indicator of acute suicide risk. Method: Literature relevant to the potential connection between eye blink rate and suicidality was reviewed and synthesized. Results: Anecdotal, cognitive, neurological, and conceptual support for the relationship between decreased blink rate and suicide risk is outlined. Conclusion: Given that eye blinks are a highly observable behavior, the potential clinical utility of using eye blink rate as a marker of suicide risk is immense. Research is warranted to explore the association between eye blink rate and acute suicide risk.

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